Troubleshooting A Broken Power Supply

February 14, 2014 by James Hobson 36 Comments

How many power bricks have died on you? Have you ever tried to fix them? Sometimes it’s easier to grab another one (they grow on trees right?), but wouldn’t it be nice to save the broken ones from filling up landfills? Depending on the cause of death, it could be a super simple fix!

[Chaim-Leib] recently purchased a powered USB hub that came with a beefy 5v, 4A power supply — it worked great — until 6 months later, when it didn’t. The company sent him a new one, and let him keep the faulty one. Looking for a challenge, [Chaim-Leib] decided to crack it open and see if he could fix it himself.

No burnt caps, no fried diodes, no burn marks anywhere in fact! Luckily he spotted the culprit: One lonely resistor had lifted up from its pad. Having never jostled or dropped the power brick, this failure likely came from some kind of stress formed during original assembly — throw in a bunch of hot and cold thermal changes, and pop goes the solder pad!

It was a simple fix with some solder, and he emailed the company photos of his operation — they’ve promised to send them on to the engineering team to further evaluate the problem.

That was easy.

Oscilloscope Repair Projects Still Probing For Success

February 1, 2014 by Mike Szczys 35 Comments

lecroy-9450-oscilloscope-repair [Luke] isn’t able to declare total victory yet. His LeCroy 9450 oscilloscope repair project has seen some success, though. The glitchy screen seen above is just one of the problems it had, but has now been fixed. When [Luke] got his hands on it, this was one of three screen states: the other two being normal operation or completely dead. Replacing the screen connector was all it took, so he moved on to the second part.

This one is much less trivial. Only one of the two channels works—which might be the point at which many would abandon the repair—but it’s still a fine single-channel scope. [Luke] continued to trouble-shoot by disassembling the bottom of the case and breaking out the device’s schematics. He traced the circuit and found one module that is suspect (and is looking for help finding a replacement). Unfortunately, the problems don’t end there. Another unknown problem is causing erroneous signals on the displayed waveforms. It’s an odd issue but it really feels like he’s close to solving this one!

The Pioneering Lifestyle In Low Earth Orbit

January 17, 2014 by Ed Van Cise (NASA Flight Director) 91 Comments

The first element of the International Space Station (ISS) launched over fifteen years ago, on November 20, 1998. For more than thirteen years at least two human beings have been continually living off the surface of our planet. Assembly of the Space Station is now complete. It is being utilized by its crews and scientists from around the world to execute its primary mission – scientific investigations that can only be accomplished in the microgravity environment of Low Earth Orbit (LEO). As with any structure, items age, wear out, or break and need to be repaired. What could be rather “simple” repairs on Earth can become much more complex in zero gravity. In some cases, “necessity becomes the mother of invention.”

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Scooby-Doo Alarm Clock Repair

January 13, 2014 by Todd Harrison 60 Comments

This is more of a hack than a repair which is a good reason for me to feature my Scooby-Doo alarm clock repair. I started out trying to simply fix some broken hardware mounts that hold the display and button mechanism within the alarm clock that looks like the Scooby-Doo Mystery Van. During testing I noticed the display was very dim suggesting an unusual current load or other malfunction, plus the alarm was not functional.

One of the coolest features of the alarm was that it made a car honking noise when the alarm was activated. Unfortunately, it turned out that the chip-onboard which produced the honking sound was shorted internally causing some transistor overheating and the dim display. It was impossible to restore functionality of the custom chip-onboard, but lucky for me the data sheets for the LM8560 clock chip revealed that it could directly output a standard alarm beeping sound to a speaker. This required the PCB and some circuitry be configured differently.

In the end the clock’s current load came down to normal parameters, the display was once again bright and the alarm functioned using the standard beeping alarm sound that comes from the LM8560 clock chip. It is sad that the coolness factor of the alarm clock cannot be restored with the honking car sound alarm but my son is quite happy to have his favorite Scooby-Doo alarm clock functioning once again.

The circuit modifications may not have been the cleverest or the best solution, so if you have other suggestions please leave them in the comments below. You can watch the video of the circuit evaluation and repair modifications after the break.

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Saving $20,000 USD With A Single LED

January 12, 2014 by Adam Fabio 81 Comments

carrier

[N8Mcnasty] is a HVAC tech who works on some big machines. One of his charges is a Carrier 19EX Chiller, rated at 1350 tons of cooling. 1 ton of cooling = 12,000 BTU. This particular chiller contained an odd LCD screen. It used a fiber optic bundle and a halogen light for backlight illumination. The system worked fine for over a decade. Now though, the halogen bulb has begun melting the glue on the fiber bundle, causing a dim display. The display in question shows some very important operating parameters, such as oil temperature, current draw, and process temperatures. Since they couldn’t easily see the display, the machine’s operators weren’t running the machine, placing stress on the other chillers in the building’s physical plant. [N8Mcnasty] tried repairing the bundle, however the glue kept melting.

A replacement display was no longer available, meaning that the entire chiller control system would have to be upgraded to a newer system. The new control system uses different sensors than the old one. This is where things start getting expensive. Replacing the sensors would also require draining the 15-20 gallons of oil, 4500 lbs of R134a refrigerant, and bringing the whole system down for almost two weeks, a $20,000 job. Rather than go this route, [N8Mcnasty] found an alternative. LED’s have come a long way since 1996, when the chiller was built. He simply replaced the halogen bulb with an LED and appropriate resistor. [N8Mcnasty] was even able to reuse the halogen bulb bracket. A bit of heat shrink tube later, and the fix looks like it was a factory option. He’s documented his fix here on reddit.

Fail Of The Week: Baby Monitor Hack Ends In Facepalm

December 19, 2013 by Mike Szczys 21 Comments

fotw-baby-monitor-repaired-the-hard-way

Editor’s Note: This was the last Fail of the Week tip we had stored up. If you want to see the series continue on a weekly basis we need help finding more documented fails! Please look back through your projects and document the ones that didn’t go quite right. We also encourage you to send in links to other fails you’ve found. Just drop the links in our tips line. Thanks!

Now on with business. This is a baby monitor which [Eric] cleverly repaired, only to realize that he more than likely did it the hard way. The monitor was broken and went unused until his son figured out how to climb out of the crib, so he figured it was time to start monitoring again. Pulling the unit from the brink of the parts bin he set to work repairing the broken power connector.

Further inspection of the power adapter showed that it was spec’d to put out 5V at 1A. This falls in line with USB power, so he clipped the end off of a USB-B cable and used a hunk of proto-board to inject the 5V lines into the device. It was when it came time to reassemble the case that he flipped the board over and discovered an existing USB-B port. He could have just cut a hole in the case to get at the connector and plugged the un-altered cable in directly. Oh well… we’re sure it was fun figuring out his own custom solution!

Fail of the Week is a Hackaday column which runs every Wednesday. Help keep the fun rolling by writing about your past failures and sending us a link to the story — or sending in links to fail write ups you find in your Internet travels.

Repairing Bose Active Noise Cancelling Headphones

December 7, 2013 by Eric Evenchick 51 Comments

[Mansour] was disappointed to find out that his Bose QC15 headphones had a dead right channel. These headphones have active noise cancelling, which uses a microphone to capture ambient noise and digital signal processing to insert an out of phase signal. Since they’re quite expensive, [Mansour] was determined to resurrect them.

First, he determined that the right speaker had died, so he found a replacement on eBay. These were designed for a different set of headphones, but matched the impedance of the original Bose part. After replacing the driver, it seemed that the repair was a failure. The sound cancelling wasn’t working, and a the playback was high-pitched. As a last attempt, he potted the speaker with glue, to match the original construction. Much to his surprise, this worked.

The problem was that the new driver didn’t have sufficient sound isolation from the microphone, which is meant to pick up passive noise. This feedback likely caused issues with the noise cancelling DSP. A little glue meant a $20 fix for a $400 pair of headphones.